Can of worms=opened.
I think the problem with Superman games is that his powers are so great, there's a limited amount of what you can do. It's basically fly, smash, etc...
They need to take it in a different direction and possibly incorporate Clark Kent into the mix, IMO.
Example;
Instead of worrying about a health meter and fighting impossibly strong bad guys, maybe incorporate a popularity meter or city damage meter.
As a living breathing entity, there is always something going on in Metropolis.
Bank Robbery? Great, go foil the crime. But if any citizens get hurt accidentally, your popularity meter drops.
Cause too much damage and the city's damage meter drops.
If one, or both get reduced to 0, the game is over (or add some other penalty).
Add in some serious story arcs involving super villians where you'll have to investigate as Clark Kent to get more information.
And perhaps changing from Clark to Sups is also something to be weary of.
This could lead to either an end of game scenario, or perhaps once your identity is blown, your loved ones like Martha Kent or Lois Lane in constant danger.
And just for kicks, maybe you decide to go all Superman III on the city.
If you go too far, maybe the JLA sends in guys like Shazaam or Martian Manhunter to take you down.
Superman is a great character but nobody seems to have the imagination to make a game worthy of him.